As is well known, image processing systems such as an electronic copying machine, digital copying machine (PPC), and facsimile apparatus use, e.g., a charge-coupled device (CCD) as an image read photoelectric conversion element in a scanner.
An optical read scanner system of reading image data with the photoelectric conversion element such as the CCD widely adopts for the main scanning direction a method of performing arithmetic processing for a digital signal in order to change the output magnification because the image read size (magnification) is determined by the number of CCD pixels and the lens magnification.
For the subscanning direction (carriage moving direction), the system adopts a method of changing the carriage moving speed to change the original width read by one main scanning line, thereby changing the magnification, a method of reading 1-page image data and changing the magnification by image processing (arithmetic processing), and the like.
However, according to the method of changing the carriage moving speed to change the subscanning magnification, when the magnification changeable range is from 25% to 400%, the carriage moving speed at a magnification of 400% must be 16 times that at a magnification of 25%.
For example, when the carriage moving speed is 200 mm/sec at a magnification of 100%, the carriage moving speed must be 50 mm/sec at a magnification of 400% and 800 mm/sec at a magnification of 25%.
To realize this, a carriage driving motor must operate within the 16-time speed range of 50 to 800 mm/sec.
To stably read an image at a high carriage moving speed of 800 mm/sec at a magnification of 25%, a very long acceleration distance and a carriage driving stabilization distance must be defined outside the image region (larger than the original size), resulting in a large device or scanner size.
If the magnification is changed by image processing (arithmetic processing) without changing the subscanning moving speed, 1-page image data must be temporarily stored in a memory after a read.
In general, the scanner reads a multilevel image. Assuming that one pixel data is 8 bits, A3-size data is consisted about 9 MB pixels at a resolution of 600 dpi. Thus, to directly store 1-page image data in the memory, A3-size data spends a memory capacity of 9xc3x978=72 MB.
To ensure this memory capacity in a semiconductor element such as a DRAM, the cost greatly increases. To ensure this memory capacity in a storage device such as a hard disk, the read/write speed of the hard disk decreases, resulting in a low processing speed.
According to a method of storing image data after binary data conversion, the magnification is changed after binary data conversion, so the image quality greatly degrades. To intermediately change the magnification, a line memory for the number of main scanning lines corresponding to the subscanning magnification must be managed to complicate calculation.
The present invention has been made to eliminate the conventional drawbacks, and has as its object to provide an image processing system including an image processing method and image processing apparatus capable of easily realizing reduction (magnification change) processing in the subscanning direction by changing the magnification in the image read subscanning direction (carriage moving direction) by both the conventional carriage moving speed change method and the signal processing method without increasing the device width (read scanner size), avoiding variations arising from high-speed carriage operation, performing any complicated arithmetic processing, or requiring any large-capacity memory in an image forming apparatus using, e.g., a charge-coupled device (CCD) as an image read photoelectric conversion element in a scanner.
To achieve the above object, according to one aspect of the present invention, there is provided an image processing method comprising the steps of:
setting a magnification for an original image to be processed;
when the set magnification is not larger than a certain magnification in reduction in changing in accordance with the set magnification a moving speed of a carriage for reading the original image to be processed, changing the carriage moving speed to 1/n (n: a natural number larger than 1) from a relationship between a current magnification and the carriage moving speed;
accumulating, in a 1-line element corresponding to a main scanning direction, an electrical signal prepared by photoelectrically converting optical image information obtained by scanning the original image to be processed by the carriage in a subscanning direction;
converting the electrical signal into a digital signal, storing 1-line input image data in the main scanning direction in reduction, performing average calculation for multilevel n-line data in the main scanning direction to change a subscanning magnification in reduction, and outputting 1-line output image data in the main scanning direction; and
performing predetermined image data processing including processing of receiving for each pixel the 1-line output image data in the main scanning direction, and converting the image data into binary data.
To achieve the above object, according to another aspect of the present invention, there is provided an image processing method comprising the steps of:
setting a magnification for an original image to be processed;
when the set magnification is not larger than a certain magnification in reduction in changing in accordance with the set magnification a moving speed of a carriage for reading the original image to be processed, changing the carriage moving speed to 1/n (n: a natural number larger than 1) from a relationship between a current magnification and the carriage moving speed;
accumulating, in a 1-line element corresponding to a main scanning direction, an electrical signal prepared by photoelectrically converting optical image information obtained by scanning the original image to be processed by the carriage in a subscanning direction;
converting the electrical signal into a digital signal, thinning out multilevel 1-line input image data in the main scanning direction to change a subscanning magnification in reduction, and outputting 1-line output image data in the main scanning direction; and
performing predetermined image data processing including processing of receiving for each pixel the 1-line output image data in the main scanning direction for each pixel, and converting the image data into binary data.
To achieve the above object, according to still another aspect of the present invention, there is provided an image processing apparatus comprising:
accumulation means for accumulating, in a 1-line element corresponding to a main scanning direction, an electrical signal prepared by photoelectrically converting optical image information obtained by scanning an original image to be formed with a carriage in a subscanning direction;
magnification setting means for setting a copy magnification of the original image to be formed;
speed change means for changing a moving speed of the carriage in accordance with the copy magnification set by the magnification setting means, and when the set copy magnification is not larger than a certain magnification in reduction, changing the carriage moving speed to 1/n (n: a natural number larger than 1) from a relationship between a current magnification and the carriage moving speed;
preprocessing means which converts the electrical signal accumulated in the accumulation means into a digital signal, has a line memory for storing 1-line input image data in the main scanning direction, performs arithmetic processing for multilevel 2-line data in the main scanning direction to change a subscanning magnification in reduction, and outputs 1-line output image data in the main scanning direction;
image data processing means for performing predetermined image data processing including processing of receiving for each pixel the 1-line output image data in the main scanning direction output from the preprocessing means, and converting the image data into binary data; and
storage means for storing at least 1-page binary data of the original image to be formed among the binary data from the image data processing means,
wherein in reduction, the carriage moving speed is changed to 1/n (n: a natural number larger than 1) a carriage moving speed in changing the subscanning magnification by the speed change means only by the carriage moving speed, and at the same time, multilevel 2-line data in the main scanning direction is converted into 1-line data by average calculation by the preprocessing means, thereby changing the subscanning magnification.
To achieve the above object, according to still another aspect of the present invention, there is provided an image processing apparatus comprising:
accumulation means for accumulating, in a 1-line element corresponding to a main scanning direction, an electrical signal prepared by photoelectrically converting optical image information obtained by scanning an original image to be formed with a carriage in a subscanning direction;
magnification setting means for setting a copy magnification of the original image to be formed;
speed change means for changing a moving speed of the carriage in accordance with the copy magnification set by the magnification setting means, and when the set copy magnification is not larger than a certain magnification in reduction, changing the carriage moving speed to 1/n (n: a natural number larger than 1) from a relationship between a current magnification and the carriage moving speed;
preprocessing means for converting the electrical signal accumulated in the accumulation means into a digital signal, performing arithmetic processing for multilevel 1-line input image data in the main scanning direction to change a subscanning magnification in reduction, and outputting 1-line output image data in the main scanning direction;
image data processing means for performing predetermined image data processing including processing of receiving for each pixel the 1-line output image data in the main scanning direction output from the preprocessing means, and converting the image data into binary data; and
storage means for storing at least 1-page binary data of the original image to be formed among the binary data from the image data processing means,
wherein in reduction, the carriage moving speed is changed to 1/n (n: a natural number larger than 1) a carriage moving speed in changing the subscanning magnification by the speed change means only by the carriage moving speed, and at the same time, multilevel 1-line data in the main scanning direction is converted into 1-line data by thinning processing by the preprocessing means, thereby changing the subscanning magnification.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.